He raised a war-chest of $32 million in January, as opposed to Hillary's relatively paltry $13.5 million. He's getting endorsements right and left, and he's winning votes from almost every single voting bloc that matters.

If Obama's opponent were anyone but a Clinton, I think it's a fair bet that he or she would have thrown in the towel by now.

But Bill and Hillary Clinton have been down so many times before, only to come springing back, phoenix-like, to conquer, that it would be foolish to count the New York senator out.

Hillary's last stand?

Clinton's entire life has been geared towardswinning the presidency [EPA]

What keeps Clinton in the race despite almost insurmountable odds must be, in part, her inability to accept the idea that she is not going to be president.

Hillary Clinton's entire life has been geared toward that goal. She bided her time, suffered the vicious attacks of the right wing, the scorn of the pundits and the humiliation of her husband's sexual peccadilloes, all with her eye on the ultimate prize.

And then, at the last minute, to have it snatched from her by this unknown, this upstart? It must indeed be a difficult concept for her to get her mind around.

And so she pushes on - now to what may well be her Alamo-like last stand in Texas and Ohio.

Bill didn't do her any favours on Wednesday, when he admitted to a crowd of supporters that if Hillary doesn't win in those two states, she cannot win the nomination.

What could possibly derail Obama at this point? A serious mistake, some colossal gaffe, some exceedingly nasty and heretofore unknown specter from his past?

It's possible, but seems unlikely. Obama is not going to self-destruct like Gary Hart did in 1988, when en route to an almost certain Democratic nomination he was inconveniently photographed aboard a yacht called Monkey Business with a cute blonde woman sitting on his lap.

Obama has shown some political misjudgments - for example, lifting whole paragraphs from a speech given by one of his supporters, Massachusetts governor Deval Patrick, and incorporating it into one of his own speeches without attribution.

That was stupid, and the Clinton campaign jumped all over it. But it didn't stick. Obama has developed his own brand of Teflon - the quality enjoyed by the original Teflon president, Ronald Reagan.

Nothing sticks to him.

There's been a lot of commentary here in the American press - some of it quite critical - about the Obamamania phenomenon; the extraordinary excitement and near-worship the candidate arouses amongst his supporters.